Wireless telecommunications systems are known. In known systems, radio coverage is provided to user equipment, for example, mobile telephones, by geographical areas known as cells. A base station is located in each cell to provide the required radio coverage. User equipment in each cell receives information and data from the base station and transmits information and data to the base station.
Information and data transmitted by the base station to the user equipment occurs on channels of radio carriers known as downlink carriers. Information and data transmitted by user equipment to the base station occurs on uplink data channels of radio carriers known as uplink carriers.
In known single uplink carrier wireless telecommunications systems, user equipment is operable to transmit data to a base station in packets. In such an arrangement, one or more Enhanced Dedicated Channel (E-DCH) dedicated physical data channels (E-DPDCH) are used to carry data from user equipment to a base station. The data throughput of a particular user equipment is determined by the transport block size carried by the one or more E-DPDCH channels per transport time interval (TTI). The transport block size sustainable on a data channel is dependent upon an allocated amount of power which that user equipment has been granted permission to use by a base station. More particularly, the amount of power the user equipment is allowed to use on a particular channel is determined by the base station in conjunction with a Radio Network Controller (RNC). The RNC sets parameters within which the network is to operate and the base station communicates with the user equipment to dictate the operation of the user equipment to meet the parameters set by the RNC.
In order for user equipment to allocate a power and therefore a transport block size to the carrier, it must receive a ‘grant’ of radio resource from a base station. In order to calculate a grant, a base station collects initial information from user equipment. The information sent from the user equipment to the base station for this task is known as a “scheduling information” (SI) message. A scheduling information message in a single carrier telecommunications network typically includes information relating to the characteristics of data to be sent from the user equipment to the base station and an indication representative of power the user equipment has available for data transmission to the base station.
A known scheduling information message comprises an encoded message sent to a base station by user equipment. A known SI message typically comprises 18 bits. The 18 bits include 5 bits which indicate the remaining power that the user equipment can use for data transmission. That information is known as the user equipment power headroom or UPH. The 18 bits further comprise 5 bits which indicate the total quantity of data in a transmission buffer of the user equipment. That information is known as the total enhanced data channel buffer status (TEBS). The 18 bit message further comprises 4 bits to indicate which logical channel having data in the user equipment transmission buffer has highest priority, and an indication of that priority. That information is known as the highest priority logical channel ID (HUD). The SI message also comprises 4 bits indicating the quantity of data in the buffer for the logical channel having the highest priority. That information is known as the highest priority logical channel buffer status (HLBS).
The total enhanced data channel buffer status (TEBS), the highest priority logical channel ID (HLID) and the highest priority logical channel buffer status (HLBS) all relate to the data to be transmitted from user equipment to a base station and are known collectively as “user equipment buffer information”. From the user equipment buffer information and the user equipment power head room (UPH), a base station can determine resource allowable for each user equipment, which indirectly determines power allocatable and a transport block size which can be transmitted by the data channel of the user equipment. A user equipment transmits user equipment buffer information and UPH encoded in the scheduling information message to a base station in order to be scheduled resource on which to efficiently transmit the complete data in the user equipment buffer to the base station.
It is proposed to allow user equipment to transmit simultaneously on more than one carrier. Each carrier is typically independently power controlled and independently scheduled by a base station. In such an arrangement, user equipment may be able to transmit data simultaneously on more than one carrier to the base station. A wireless telecommunications network allowing for user equipment to transmit on two or more carriers simultaneously, or a base station to transmit simultaneously on two or more carriers is known as a “multi-carrier” network. Such multi-carrier wireless telecommunications networks may provide two carriers, and may be referred to as a “dual cell high speed up link packet access” (DC-HSUPA) network. Networks having more than two carriers may be referred to as “multi cell high speed up link packet access” (MC-HSUPA) networks. The term “multi-carrier” network used herein is envisaged to cover both DC-HSUPA and MC-HSUPA networks.
Accordingly, it is desired to provide an improved technique to encoding and transmitting information relating to data to be transmitted from user equipment to a base station in a multi-carrier wireless telecommunications network.